A338760 - OEIS

A338760

Subword complexity of a certain infinite word.

1, 2, 4, 8, 15, 28, 47, 73, 107, 150, 203, 267, 343, 432, 535, 653, 787, 938, 1107, 1295, 1503, 1732, 1983, 2257, 2555, 2878, 3227, 3603, 4007, 4440, 4903, 5397, 5923, 6482, 7075, 7703, 8367, 9068, 9807, 10585, 11403, 12262, 13163, 14107, 15095, 16128, 17207

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OFFSET

0,2

COMMENTS

The infinite word is (ab)(aab.abb)(aaab.aabb.abbb)(aaaab.aaabb.aabbb.abbbb)... . Subword complexity is the number of distinct length-n blocks appearing in the sequence.

LINKS

Table of n, a(n) for n=0..46.

L. Schaeffer and K. Wu, Two Infinite Words with Cubic Subword Complexity, J. Integer Sequences 23 (2020), Paper 20.10.8.

FORMULA

Equal to 2^n for n <= 3, and n^3/6+n^2/2-5n/3+3 for n >= 4.

EXAMPLE

For n=4 the only word omitted is baba.

CROSSREFS

Cf. A338761.

Sequence in context: A284275 A054159 A222028 * A056181 A101976 A339656

Adjacent sequences: A338757 A338758 A338759 * A338761 A338762 A338763

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, Nov 07 2020

STATUS

approved